OS Detection with platform module doesn't support Python 3.9

[diastelo]

Some of the functions used in the OS version detection section of bootstrap.py have been deprecated and removed. I got an error on RHEL 9 that platform.dist and platform.linux_distribution() don't exist. There was a recommendation to switch to the distro module in an issue tracker for the platform module, but this doesn't ship with platform-python.

[stanlog]

I've got the same issue :
`Foreman Bootstrap Script
This script is designed to register new systems or to migrate an existing system to a Foreman server with Katello
Traceback (most recent call last):
File "/root/bootstrap.py", line 1142, in
RELEASE = platform.linux_distribution()[1]
AttributeError: module 'platform' has no attribute 'linux_distribution'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/root/bootstrap.py", line 1145, in
RELEASE = platform.dist()[1]
AttributeError: module 'platform' has no attribute 'dist'`

RHEL 9 / Python 3.9